Longitudinal splitting and grouting in deep buried rock layers based on the coupling effect between slurry and rock

The coupling effect between slurry and a fractured rock layer controls the width of the fracturing channel and the grouting pressure. This effect is attenuated as the slurry diffusion front spreads from the grouting hole. This study examined the motion of slurry and the fracture expansion process, thereby establishing a longitudinal grout-splitting model of slurry-rock coupling by deriving a slurry-splitting diffusion motion equation that considers the time-varying viscosity of the slurry and attenuation of the fracture width. Research has demonstrated that in the initial stage of grouting, the plastic viscosity of the slurry is low, making grouting pressure and grouting rate the main determinants of the slurry's splitting and diffusion range, as both factors can significantly expand the diffusion range of the slurry. However, once the viscosity of the slurry exceeds a certain threshold, viscosity becomes the primary factor that restricts the diffusion range of the slurry. Therefore, when using a slurry with time-varying viscosity, a higher initial grouting rate and grouting pressure should be selected in the early stages of grouting. As the grouting pressure stabilizes, the viscosity of the slurry should be appropriately increased to enable the slurry to quickly gel and seal the fractures.